<mat-toolbar color="primary">
  <mat-nav-list><a mat-list-item routerLink="all">All tasks</a></mat-nav-list>
  <mat-nav-list><a mat-list-item routerLink="overdue">Overdue tasks</a></mat-nav-list>
  <mat-nav-list><a mat-list-item routerLink="add">Add task</a></mat-nav-list>
</mat-toolbar> 
<div>
  <router-outlet></router-outlet>
</div>
